TextTrackList

TextTrackList is an interface in the HTML specification that represents a list of text tracks associated with a media element. A text track can be a caption, subtitle, or metadata track. The TextTrackList object is read-only and is accessed through the textTracks property of an HTMLMediaElement (like HTMLVideoElement or HTMLAudioElement).

The TextTrackList interface provides a way to access and iterate over the available text tracks. It behaves like an array, allowing access to individual tracks by their index. Key properties include the length, which indicates the number of tracks in the list. Common methods include getTrackById(id), which retrieves a specific track by its unique ID, and there are also methods for adding and removing tracks, although these are typically not used directly on the TextTrackList itself but rather on the media element's textTracks collection.

Each item within a TextTrackList is a TextTrack object, which describes the properties of an individual text track, such as its kind (e.g., captions, subtitles), language, label, and mode (e.g., showing, hidden, disabled). Developers can use TextTrackList to programmatically control which text tracks are displayed or available to the user, for example, by changing the mode of a track. This is crucial for accessibility features and internationalization of media content.